Multi-range on-site full-automatic pressure calibration instrument

ABSTRACT

Provided is a multi-range field full-automatic pressure and electric signal calibrating instrument, comprising: control components such as a shell, a power switch, multiple-interfaces, a display, a keyboard, and a gas pressure generating unit, a power supply unit, a pressure detecting unit, a gas pressure control unit and an electric signal detecting unit; the pressure output end of the pressure control unit is in parallel connection with pressure joints which are used for installing multiple pressure standard meters and detected meters with different ranges; the pressure control unit is in signal connection with the pressure standard meters; the electric signal detecting unit is in signal connection with the pressure control unit and the detected meters; the power supply unit can supply power by batteries. The calibrating instrument does not need to be externally connected with a gas cylinder and an alternating current power supply and can automatically generate a gas pressure and generate an accurate standard pressure; the design of the multi-range pressure standard meter can be suitable for various detected meters; the double detection and calibration for pressure and electric signals can be implemented; the weight and volume of the instrument are small; and the multi-range field full-automatic pressure and electric signal calibrating instrument is convenient to carry in the field and can carry out automatic calibration on various field pressure instruments.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 14/122,087, filed onNov. 25, 2013. These prior U.S. application and the present continuationapplication claim the benefit of priority of China Patent ApplicationNo. 201110139064.6, filed on May 26, 2011. The disclosures of theseprior U.S. and foreign applications are incorporated herein byreference.

TECHNICAL FIELD

The present invention pertains to the area of measurement andcalibration of pressure instrumentation, and mainly relates to automatedcalibration in that area. More particularly, it relates to an automatedcalibration equipment that is convenient to be carried to field,performs both calibration of pressure and output electric signals onpressure instruments, and can switch standard ranges.

BACKGROUND OF THE INVENTION

In the areas of industrial production, pressure measurement, etc.,on-site verification or calibration needs to be carried out on all theutilized pressure gauges, after used for a certain period of time, inorder to determine whether a pressure gauge is accurate.

In conventional pressure calibration instruments, operation is carriedout in a closed pressure calibration pipe, where gas pressure isgenerated through manual pressurization, and pressure instrumentindications are read out by observation, and where the gas pressure isregulated in a manual pressurizing manner. The effect of the regulationis to provide, at a pressure output port, a certain accurate gaspressure as a standard pressure for access of pressure instruments to becalibrated, so as to perform calibration on various pressureinstruments.

However, such a conventional pressure calibration manner involves humanobservation and manually operated pressure regulation, suffers fromlarge observation errors, and is time and effort consuming Especially inan industrial field or within a small pressure range, when performingpressure detection, manually adjusting pressure is not easilystabilized, observation is greatly affected by human disturbancefactors, and working efficiency is quite low.

To solve this problem, increasing the working efficiency of pressuredetection, in recent years, many companies have developed conventionalpressure controllers. The pressure controller and an externallyconnected gas cylinder together form a device system. In a closedpressure calibration pipe, the gas cylinder provides a gas pressureaccording to a set pressure, and through automatic monitoring of apressure sensor and automatic control of a pressure regulator, a setpressure output is provided for access of pressure instruments to becalibrated, so as to perform automatic calibration on the pressureinstruments. This method overcomes the disadvantages of humanobservation and manually operated pressure regulation, can automaticallymonitor and adjust the pressure, and significantly improves the workingefficiency.

Nonetheless, the conventional pressure controller is not portable due toits own large volume, the use of AC power supply for supplying power,large volume of the external gas cylinder, and place restriction onchemical gases within the cylinder, etc. For a large number of fieldused pressure instruments, there exists the disadvantage thatcalibration can not be implemented on-site.

As for a digital pressure instrument such as a pressure transducer,whether its output signal value is accurate or not directly affects themeasured pressure thereof. Therefore, for such a digital pressureinstrument, in addition to magnitude calibration for pressure of theinstrument, magnitude calibration for electric signals (current,voltage, and switch pulse) thereof is also required. Among prior artfull-automatic pressure calibration technologies, there is not yet atechnology capable of integrating pressure calibration and electricsignal calibration.

On the other hand, in prior art pressure controllers, typically onepressure sensor is used as a standard device and is incorporated in theinstrument. In prior art pressure controllers, there are also cases ofusing two pressure sensors, where one is used as a pressure standarddevice, and the other is used to measure atmospheric pressure. In eithercase, the measuring range is a fixed single range, limiting pressuremeasurement and control range of the instrument. For some measuringranges, unless another pressure controller with corresponding range isused, measurement accuracy will be affected by the measuring ranges.This requires a plurality of multi-range pressure controller devices atthe time of pressure instrument calibration, causing inconvenience toon-site detection.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an automated standardpressure and current signal calibration device that can overcome theabove defects, is convenient to carry, and is suitable for use in theindustrial field, namely, a multi-range on-site full-automatic pressureand electric signal calibration instrument.

To achieve the above object, the present invention provides thefollowing technical solutions.

A multi-range on-site full-automatic pressure and electric signalcalibration instrument, comprising: a housing; operation and controlcomponents including a power switch, a plurality of interfaces, adisplay, a keyboard, etc. incorporated at proper positions in thehousing; and a gas pressure generation unit, a power supply unit, and apressure detection unit incorporated in the housing, and furthercomprising a gas pressure control unit and an electric signal detectionunit, wherein the gas pressure generation unit is a gas pressurizingpump communicated with atmosphere, a pressure output pipe thereof beingcommunicated with the gas pressure control unit; a pressure output portof the pressure control unit is communicated in parallel with twopressure connectors, one for installation of a gauge to be calibrated inthe pressure detection unit and the other for installation of a pressurestandard device in the pressure detection unit, the pressure standarddevice being a manually replaceable standard gauge of a different rangeor a plurality of switchable pressure modules of different ranges; thepressure control unit is in signal connection with the pressure standarddevice in the pressure detection unit, the electric signal detectionunit is in signal connection with the pressure control unit and thegauge to be calibrated in the pressure detection unit, and the powersupply unit is in electrical connection with the gas pressure generationunit, the pressure control unit, the pressure detection unit and theelectric signal detection unit, respectively.

The gas pressurizing pump comprises a motor, an eccentric shaft, a swingrod, a pump body, a left cylinder body and a right cylinder body, apiston rod, and an one-way valve body and a cylinder head attached toeach of the cylinder bodies, wherein the pump body is a connectingmember, the motor is fixed to the pump body, and a motor shaft extendsinto the pump body and is connected with the eccentric shaft; theeccentric shaft is of a cylindrical shape, and has a driving pindeviated from the axis at one end thereof, with the driving pinextending through a mounting hole in the flat-shaped swing rod; theswing rod is connected to the horizontally disposed piston rod through ascrew; the piston rod is of a cylindrical shape, opposite ends thereofbeing mounted with sealing rings and extending into the left and rightcylinder bodies, respectively; the cylinder body is of a cylindricalstructure, and the two cylinder bodies are mounted at opposite ends ofthe pump body, respectively; the two cylinder bodies are sequentiallyprovided at outer ends thereof with the one-way valve bodies and thecylinder heads, the one-way valve bodies being communicated with innercavities of the cylinder bodies, and communicated with external air orcompressed air lines through passages in the cylinder heads.

In the gas pressurizing pump, the piston rod forms sealing, through thesealing rings mounted at the opposite ends thereof, at an inner wall ofthe cylinder bodies; and a swing motion of the swing rod drives thepiston rod to reciprocate within the two cylinder bodies along the axis.

In the gas pressurizing pump, the outer end of each of the cylinderbodies is mounted with two reversely disposed one-way valve bodies,wherein one of the one-way valve bodies is communicated with theexternal air, and the other of the one-way valve bodies is communicatedwith the compressed air line.

In the gas pressurizing pump, the one-way valve body is formed throughassembly of a cavity seal body, an elastic arm, a metal pad, and asealing ring, wherein the elastic arm extends inwardly from the cavityseal body and is coupled with a top end of the metal pad, and a bottomend of the metal pad fixes the sealing ring.

In the above multi-range on-site full-automatic pressure and electricsignal calibration instrument, the power supply unit is a self-poweredsystem by battery, or an external power source.

The pressure control unit comprises a pressure controller and asingle-chip microcomputer system, wherein a gas path portion of thepressure controller includes an intake valve, a buffer, a micro-pressureadjusting mechanism, an exhaust valve, and a standard pressure outputport; the standard pressure output port is provided with two pressureconnectors connected in parallel; the intake valve is communicated witha high pressure gas output pipe of the gas pressurizing pump; the bufferis a pressure accommodating chamber used to stabilize and preserve gaspressure output by the intake valve, an outlet port of the buffer iscommunicated with a cylinder in the micro-pressure adjusting mechanism,and a plunger in the cylinder is connected with a screw mechanism; theexhaust valve is installed in a pressure output pipe and is communicatedwith the atmosphere to discharge gas pressure, and the standard pressureoutput port is installed in the pressure output pipe in parallel withthe exhaust valve; a control portion of the pressure controller includesa pressure regulation driving circuit, which is in electrical connectionwith the power supply unit, and is in signal connection with the intakevalve, the exhaust valve and the screw mechanism; the single-chipmicrocomputer system includes a control chip loaded with a pressurecontrol algorithm, and is provided with a plurality of interfaces; thecontrol chip is connected to the pressure regulation driving circuit,and controls the pressure output pipe through the driving circuit tooutput a precise standard pressure. The plurality of interfaces providedin the single-chip microcomputer system are a digital communicationinterface connected to the pressure standard device, a displayinterface, a keyboard interface, and a RS232 interface connected to anexternal device. The exhaust port of the exhaust valve is furtherinstalled with a muffler.

In the above multi-range on-site full-automatic pressure and electricsignal calibration instrument, the electric signal detection unitcomprises an electric signal detection circuit, an electric signal inputand output terminal and a pressure switch signal input terminal of thegauge to be calibrated are connected to a signal amplifier respectively,then through an A/D converter, an electric signal is converted into adigital signal which is input to the control chip of the single-chipmicrocomputer system, and through calculation by a calculation formulapreset in the control chip, a detected electric signal value or on/offstatus information of the pressure switch is obtained, and is thendisplayed by the display. The on/off signal information of the pressureswitch is also used in the control chip for program determination onpressure output values measured at a corresponding state.

In the above multi-range on-site full-automatic pressure and electricsignal calibration instrument, the pressure standard device is astandard gauge selected from a precision digital pressure gauge, adigital pressure calibrator, or an intelligent digital pressurecalibrator provided with the above electric signal detection circuit, orthe pressure standard device is a plurality of pressure modules withdifferent ranges, each communicated through a respective solenoid valvewith one of the pressure connectors at the standard pressure output portof the pressure controller, the solenoid valve being controlled by thecontrol chip through a valve switching circuit; the single-chipmicrocomputer system further comprises a pressure module output signalswitching element, through which an output signal of each pressuremodule is output to the control chip via the digital communicationinterface.

By taking the above design, the present invention has the followingcharacteristics:

(i) requiring no external AC power supply, and convenient to carry tofield;

(ii) requiring no external gas cylinder, reducing weight and volume, andconvenient to carry on-site;

(iii) continuously on-site battery-powered, and capable of implementingon-site pressure calibration; and

(iv) capable of automatic calibration on pressure and electric signalsfor pressure instruments of different types and various ranges.

The present invention requires no external gas cylinder or AC powersource, and can automatically generates gas pressure. In a closedpressure calibration pipe, through automatic measurement and regulationon the auto-generated gas pressure, a certain accurate gas pressure isproduced at the pressure output port, as a standard pressure provided tothe pressure instrument to be. calibrated. The present invention isequipped with a plurality of standard gauges of different ranges, canperform exchange of a standard gauge of a corresponding range fordifferent pressure detection ranges, and is thus readily adaptable todifferent user configurations. Pressure modules are used as the pressurestandard device, can be incorporated in the controller and easy tocarry, thus facilitates portability of the instrument, meanwhilepressure modules of different ranges are connected in parallel andswitched for use, which can also facilitate calibration on calibratedgauges of different ranges. The present invention also combines anelectric signal detection circuit, to perform detection and calibrationon electric signals output by the calibrated gauge while performingpressure calibration on it, thereby implementing integrated calibrationon pressure and electric signals. The present invention uses its ownbattery for power supply, requiring no external AC power source. Thepresent invention also uses its own miniature pressure pump to generategas pressure for supply to the pressure calibration loop, requiring noexternal gas cylinder. Taking the above design, the present inventionnot only achieves full-automatic calibration, but also increases theaccuracy through the combined calibration on pressure and electricsignals, while greatly reducing the weight and volume of the calibrationinstrument, facilitating on-site portability. The present inventionachieves automated calibration on pressure instruments and significantlyimproves working efficiency while implementing on-site calibration on alarge number of field used pressure instruments, thus can performautomated calibration on a variety of on-site pressure instruments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of the on-site full-automatic pressurecalibration instrument of the present invention.

FIG. 2 is an overall block diagram of the internal configuration of thepresent invention.

FIG. 3 is a block diagram showing the configuration of the pressurecontrol unit of FIG. 2 and its connection with other units.

FIG. 4 is a structure diagram of the preferred miniature pressure pumpof the present invention.

FIG. 5 is a structure diagram of the preferred one-way valve used in theminiature pressure pump of the present invention.

FIG. 6 shows the power supply/charge control circuit used in the presentinvention.

FIG. 7 shows the electric signal detection circuit used in the presentinvention.

DETAIL DESCRIPTION OF THE EMBODIMENTS

Referring to FIGS. 1, 2 and 3, the present invention provides an on-sitefull-automatic pressure calibration instrument, comprising: a housing 9;a gas pressure generation unit 1, a pressure control unit 2, an electricsignal detection unit 5, a power supply unit 3, and a pressure detectionunit 4 assembled respectively within the housing 9; a display 91, akeyboard 92, electric signal output ports 93 appropriately distributedfor convenient use, a power switch 94 and a RS232 interface 95, etc.disposed on the top of the housing 9; a plurality of receiving grooves(not shown in the figures) provided in the internal space of the housing9 for installation of standard gauges with different ranges forreplacement, wherein the gas pressure generation unit 1 is provided witha gas path input port (inlet port) 96 communicating with the atmosphere,and an output port communicating with the pressure control unit 2; thepressure control unit 2 has a gas path output port 29 communicating withthe pressure detection unit 4 (the thick lines in FIG. 2 indicating gaspath connections), and is connected respectively with the gas pressuregeneration unit 1, the pressure detection unit 4, and the electricsignal detection unit 5 through signal lines (the thin lines in FIG. 2indicating data signal connections) for pressure control; and the powersupply unit 3 is connected respectively with the gas pressure generationunit 1, the pressure control unit 2, the pressure detection unit 4, andthe electric signal detection unit 5 through electric wires (themedium-thickness lines in FIG. 2 indicating power supply lineconnections) for power supply.

The gas pressure generation unit 1 generates gas pressure by a gaspressurizing pump. The gas pressurizing pump directly communicates withthe atmosphere, and generates gas pressure through compressing airwithout an externally connected gas cylinder. Theoretically, any gaspump that can generate gas pressure through compressing air isapplicable in the present invention. In the present invention, a gaspressurizing pump developed by the applicant is preferably used, whichhas functional properties of automatic pressurization, high pressure ofpressurization, and high efficiency of pressurization, and uses atechnique of high-pressure one-way valve.

The gas pressurizing pump used in the present invention is a highpressure bidirectional miniature electric gas pump (miniature pressurepump), the structure of which is shown in FIG. 4, and which comprises amotor 11, an eccentric shaft 12, a swing rod 13, a pump body 14, a leftcylinder body 15 and a right cylinder body 15′, one-way valve bodies 16and a piston rod 10. The pump body 14 is a connecting member. The motor11 is fixed to the pump body 14 by a motor bracket 112, with a motorshaft extending downwardly into the pump body 14 via a coupling 113 andconnected with the eccentric shaft 12. The eccentric shaft 12 is of acylindrical shape and has a driving pin 121 deviated from the axis atone end thereof, with the driving pin 121 extending through a mountinghole in the flat-shaped swing rod 13. A screw 111 extends throughanother mounting hole in the swing rod 13 to couple the swing rod 13 tothe horizontally directioned piston rod 10, with a gap between the swingrod 13 and the piston rod 10 being self-adjustable through a mountingdistance given by the screws 111. The piston rod 10 is of a cylindricalstructure, with sealing rings 19 mounted at opposite ends thereof. Theopposite ends of the piston rod 10 extend into the left cylinder body 15and the right cylinder body 15′, respectively. The cylinder body is of acylindrical structure, and the two cylinder bodies 15 and 15′ aremounted at opposite ends of the pump body 14, respectively. The pistonrod 10 forms sealing, through the sealing rings 19 mounted at theopposite ends thereof, at an inner wall of the cylinder bodies 15 and15′. After symmetrical and bidirectional assembly of the cylinder bodies15 and 15′ at the opposite ends, upon swinging the swing rod 13 drivesthe piston rod 10 to reciprocate along the axis, and at the same timethe sealing rings 19 at the opposite ends become guide rings for thepiston rod 10, thereby structurally realizing a manner of self-aligningguidance, and achieving driving and sealing of the gas pump. The twocylinder bodies 15 and 15′ are sequentially provided at outer endsthereof with cylinder head gaskets 18, the one-way valve bodies 16, andcylinder heads 17 fixedly mounted at the opposite ends of the pump body14, where two one-way valve bodies 16 are mounted in mutually reversedirections, respectively at each of the opposite ends of the pump body14. The one-way valve bodies 16 communicates with inner cavities of thecylinder bodies 15 and 15′, and communicates with external air orcompressed air lines through passages in the cylinder heads 17. Theone-way valve bodies 16 are mounted in the same gas inlet and outletdirections as those shown in FIGS. 4 and 5.

Here, refer to FIG. 5 for structure of the one-way valve body 16, whichcomprises a cavity seal body 161, an elastic arm 162, a metal pad 163,and a sealing ring 164, wherein the cavity seal body 161 is of anannular structure, is an outer support and seal for the whole structure,is disposed between two planes to be sealed (between the cylinder headand the cylinder body), forms a sealed cavity, also used as a seal forthe overall structure, and is made of elastic material; the elastic arm162 is of a strip-like structure extending inwardly from the cavity sealbody 161, and can be stretched and retracted by its rubber elasticity,with a bottom of the elastic arm 162 abutting against a top of the metalpad 163; the metal pad 163 is disc-shaped, having an upper annular slot131 for embedding an extended end of the elastic arm 162 such that it isengaged into the slot 131 and that a bottom surface of the elastic arm162 abuts against the top of the metal pad 163, and the metal pad 163 isprovided at a bottom thereof with an annular groove 132 for placing thesealing ring 164 therein; the sealing ring 164 is a standard O-ring, andis fixed within the groove 132 in the bottom of the metal pad 163.During installation, the one-way valve body 16 is of gas inlet andoutlet directions consistent with those of the miniature pressure pump 1(shown in FIG. 4), forming one-way inlet gas. When high pressure gas isdischarged (exhausting), the piston 10 in the cylinder body 15 movesleftward to compress gas within the cylinder, and an one-way valve 16mounted at a lower side is operated, pushing a side of the metal pad 163embedded with the O-ring 164 to move (in the gas outlet direction) alongwith the sealing ring. As a result, the one-way valve body 16 is in anopen state, and the compressed high pressure gas is pushed into a highpressure gas output pipe through a gas passage. When the piston rod 10in the cylinder body 15 is in a return stroke, the elastic arm 162causes the metal pad 163 to move backward (in an opposite direction tothe gas inlet direction), compressing the sealing ring 164 so as to forma surface sealing, such that the high pressure gas is enclosed in thedesired cavity, and a requirement of high pressure closure is fulfilled.When the external air is intaken (suctioning), the piston 10 in thecylinder body 15 moves rightward to form a negative pressure with gas inthe cylinder, and an one-way valve 16 mounted at an upper side isoperated, pushing a side of the metal pad 163 embedded with the O-ring164 to move (in the gas outlet direction of FIG. 5) along with thesealing ring. As a result, the one-way valve body 16 is in an openstate, and the external air is intaken into the cylinder body 15 througha gas passage. Throughout the entire process, the cavity seal body 161isolates the high pressure gas from the external environment, whilesupporting through the elastic arm 162 connected thereto the metal pad163 and the sealing ring 164, thereby forming an integrated sealing.Since at each end of the pump body 14 are mounted two one-way valvebodies 16 in mutually opposite orientations with one for intake controland the other for exhaust control, an one-direction gas movement isformed during the reciprocating motion of the piston 10, and compressedgas is generated when gas is placed in the closed spaces.

When the miniature pressure pump of such a structure is operating, themotor 11 drives the eccentric shaft 12 to rotate, and the driving pin onthe eccentric shaft 12 pulls the piston rod 10 through the swing rod 13and the screw 111, so that the piston rod 10 can reciprocate. The pistonrod 10 forms sealing with the cylinder body 15 through the sealing rings19 mounted at the opposite ends thereof. A process of generating highpressure gas will now be described, taking the left part of the cylinderas an example. When the piston rod 10 moves rightward, the inner spaceof the left cylinder body 15 increases rapidly, forming a negativepressure inside the cylinder body 15, so that the upper left one-wayvalve body 16 is placed in an intake state (the reversely disposedone-way valve core is opened), and the external air is intaken into thecylinder body 15. Till the swing rod 13 moves to a right limit position,the reversely disposed one-way valve body 16 is closed, and the intakeprocess is completed. When the piston rod 10 moves leftward, the sealedgas inside the left cylinder body 15 is compressed with the pressuregradually increased, so that the lower left one-way valve body 16 isplaced in an exhaust state (the forwardly disposed one-way valve core isopened), and the compressed air is discharged. Till the swing rod 13moves to a left limit position, the forwardly disposed one-way valvebody 16 is closed, and the exhaust process (of delivering high-pressurecompressed gas) is completed. The motor drives the eccentric shaft 12,and then causes the piston rod 10 to reciprocate through the swing rod13. Thus, the intake process and the exhaust process are repeatedcontinuously, and gas is compressed continuously generating highpressure gas. The symmetrical and bidirectional placement of thecylinders 15 and 15′ can perform twice during one cycle the operationsof intaking air from outside and discharging compressed gas from withinthe cylinders, which also improves efficiency.

The gas pressure generation unit 1 is a high pressure generation end inthe present invention, It uses the miniature pressure pump to intake airfrom outside, compress the air and exhaust the compressed gas throughthe pipe to generate high pressure. It then cooperates with a pressurecontroller and a pressure standard device to implement real-timemeasurement and transmission of pressure. Through automatic measurementand regulation of the pressure, a certain accurate gas pressure isgenerated or produced at a pressure output port, as a standard pressureprovided for pressure instruments to be calibrated.

The pressure control unit 2 achieves control of gas pressure through apressure controller and a single-chip microcomputer (SCM) system. Asshown in FIG. 3, a gas path portion of the pressure controller includesan intake valve 21, a buffer 22, a micro-pressure adjusting mechanism23, an exhaust valve 24 (refer to FIG. 1 for layout position), a muffler25, and a standard pressure output port 29. The standard pressure outputport 29 is connected in parallel with a pressure connector 27 of acalibrated gauge and a pressure connector 26 of a pressure standarddevice. When the pressure standard device is a standard gauge, thestandard gauge 60 is directly connected to the pressure connector 26,and by manual replacement of a standard gauge 60 of a different range,calibration is performed on a gauge to be calibrated of a correspondingrange. However, when the pressure standard device is a pressure module(pressure sensor), the pressure connector 26 is communicated withpressure modules 61 or 62 respectively by a plurality of solenoid valves31 or 32, and is switched to the pressure module 61 or 62 of a differentrange through a valve switching circuit 30. The above components arecommunicated respectively via gas paths (the thick lines in FIG. 3indicating gas paths). A control portion of the pressure controller 2includes a pressure regulation driving circuit 20 and the valveswitching circuit 30. The SCM system comprises a control chip 28 loadedwith a pressure control algorithm and an electric signal (voltage,current) algorithm, and is provided with a plurality of interfaces, suchas a digital communication interface (connected to the standard gauge 60or connected to the pressure modules 61 and 62 via a sensor switchingelement), a display interface (connected to the display 91), a keyboardinterface (connected to the keyboard 92), and a RS232 interface 95 tofacilitate connections with external devices when necessary, and thelike. The pressure regulation driving circuit 20 is connected to thepower supply unit via a power supply line (indicated by themedium-thickness lines in FIG. 3), and is connected respectively to theintake valve 21, the micro-pressure adjusting mechanism 23, the exhaustvalve 24, and the control chip 28 via signal lines (the thin lines inFIG. 3 indicating signal lines for pressure control). When the miniaturepressure pump shown in FIG. 4 is used as the gas pressure generationunit 1, the pressure regulation driving circuit 20 is further connectedto the motor 11 of the miniature pressure pump via a signal line tocontrol operations thereof. The valve switching circuit 30 is connectedto the plurality of solenoid valves 31 and 32 and the control chip 28via signal lines (indicated by the thin lines in FIG. 3) to controloperations of the pressure modules through opening and closing of thesolenoid valves.

The intake valve 21 is communicated with the high pressure gas outputpipe of the miniature pressure pump 1 and functions as a pressure inputport to the pressure controller. A pressure output port 29 of thepressure controller is the two pressure connectors 26, 27 connected inparallel. The buffer 22 is a pressure accommodating chamber of a fixedshape (e.g., an elliptical cylinder shape), mainly used to filterfluctuations in air flow entering through the intake valve 21, stabilizeand preserve gas pressure. The gas passing through the buffer 22 entersthe micro-pressure adjusting mechanism 23. The micro-pressure adjustingmechanism 23 comprises a cylinder and a plunger installed in thecylinder. The plunger is connected with a screw mechanism (reference canbe made to the Chinese Patent No. ZL200720190548.2, “Automaticmicro-pressure generator”), and the screw mechanism is connected to anda feed thereof controlled by the pressure regulation driving circuit 20.Driven by the screw mechanism, the plunger performs linear displacementin the cylinder, so as to change the volume of gas compression withinthe cylinder and to deliver the compressed gas. The output gas pressurepasses through the micro-pressure adjusting mechanism 23 to achieveaccurate control and regulation on pressure. The exhaust valve 24 isinstalled in the output pipe to discharge gas pressure. It is controlledby the pressure regulation driving circuit 20 to open and close in orderto adjust the discharge of the gas pressure. It may further be connectedto a muffler 25 for purpose of eliminating airflow friction soundgenerated when discharging the gas pressure. The pressure connectors 26,27 and the exhaust valve 24 are connected in parallel via gas paths toensure the same output pressure. The control functions of the pressureregulation driving circuit 20 are performed under the drive of thecontrol chip 28 of the SCM system, mainly to implement electric controlon the open/close state of the intake valve 21 and the exhaust valve 24,so as to achieve regulation on gas inflow or discharge pressure, and toimplement control on the displacement of the plunger within themicro-pressure adjusting mechanism 23 by controlling the feed of thescrew mechanism, so as to achieve regulation on the output pressure bychanging the volume of gas compression in the cylinder.

The SCM system includes the embedded control chip 28, and the displayinterface, the keyboard interface and the digital communicationinterface, and may also be provided with a RS232 interface 95. Thecontrol chip 28 is embedded therein with a pressure control algorithm(such as the well-known special adaptive PID control algorithm) and anelectric signal (voltage, current) algorithm. The digital communicationinterface of the SCM system, when the pressure standard device is astandard gauge, can directly receive a pressure value displayed andreturned by the standard gauge 60. However, when the pressure standarddevice is a plurality of pressure modules (of different ranges), througha module switching element (e.g., a locator), a pressure value of thelocated pressure module 61 or 62 is returned to the control chip 28through the digital communication interface. Through comparison with apreset pressure value in the chip, the pressure control algorithmcalculates a control amount based on the difference value, and thentransmits the calculated control amount to the pressure regulationdriving circuit 20. The pressure regulation driving circuit 20 thusachieves control on the intake valve 21, the exhaust valve 24 and themicro-pressure adjusting mechanism 23, thereby implementing a feedbackcontrol in which pressure occurs precisely. The control chip 28 as wellas the pressure regulation driving circuit 20, the valve switchingcircuit 30 and the pressure standard device 6 constitute a pressureoutput control unit for real-time control of pressure output. Thecontrol chip 28 as well as the pressure regulation driving circuit 20,the calibrated instrument 7, and the external display 91 and keyboard 92of the SCM system constitute a pressure measurement and control unit,wherein set pressures and programmable operation data and parameters areinput through the keyboard 92, and pressure control results and curvesare displayed through the standard gauge 60 or the display 91. Thecontrol chip 28 is further connected to the electric signal detectionunit 5, to implement detection and calibration on output signals of thecalibrated gauge (refer to FIG. 3, the thin lines indicating signalconnections). The RS232 interface 95 is reserved for use in conditionaldetection environments, and can be connected with other externaldevices, such as an external computer (refer to FIG. 2), a printer, etc.

The operation of the pressure control unit 2 is as follows. A pressurevalue is set according to the range of a pressure gauge 7 to becalibrated, and is used as a set pressure control value. The pressurecontrol value is input to the control chip 28 via the keyboard 92. Thepressure regulation driving circuit 20 drives the motor 11 of theminiature pressure pump to operate thereby generating high pressure gas.A value is read out through the standard gauge 60 connected to thepressure connector 26 (or recorded by a pressure sensor 61 or 62, arange of which matches that of the pressure gauge 7 to be calibrated,and which is selected through the valve switching circuit 30), and theoutput pressure value is returned to the control chip 28. The controlchip 28 compares the output pressure with the pressure control value,calculate a control amount based on the difference value, and transmitsthe calculated control amount to the pressure regulation driving circuit20. The pressure regulation driving circuit 20 performs control on theintake valve 21, the exhaust valve 24 and the micro-pressure adjustingmechanism 23. Until the output pressure value is equal to the setpressure control value, the precise control of the output pressure iscompleted.

Thus, in a closed pressure calibration pipe, through fine adjustment ofthe plurality of pressure control regulators (the intake valve, theexhaust valve) and the micro-pressure adjusting mechanism, the pressurecontrol unit performs setting control on the gas pressure, and outputsan accurate gas pressure at the pressure output port. Based on theaccurately output gas pressure value, an accurate pressure calibrationis carried out on the pressure gauge to be calibrated.

The power supply unit 3 is primarily a battery pack equipped in theinstrument. It can maintain power supply without an external powersource at the same time, making it possible to be carried to field. Incase power is available in the field, the power supply unit may also beconnected to an external power source (refer to FIG. 2), and supplypower by the external power source. In addition, the external powersource can also charge the battery pack.

The battery pack power supply unit used in the present invention may bea conventional DC power supply system, preferably a power supply systemwith functions of battery power supply monitoring, control andprotection, as well as battery pack power supply and charge control.Used herein is the power supply/charge control circuit disclosed in theChinese Patent No. ZL200620119089.4, “Power supply/charging controlcircuit,” as shown in FIG. 6, in which circuit the AC/DC power supplyterminal is connected to an external power source, and the instrumentpower supply terminal is the current output terminal. Power istransmitted respectively to other units in the pressure calibrator, asshown in FIG. 2. The power supply unit can ensure good DC power supplyperformance, no power supply interruption, good battery chargingperformance, safe use of battery, and extended life span. When used inthe pressure calibrator, it enables the pressure calibrator to beaccurate in detection, safe and reliable, of long operating time, andconvenient to be carried for field application.

The pressure detection unit 4 includes pressure standard devices of atleast two ranges so as to be able to perform calibration on calibratedgauges of different ranges. The pressure standard device 6 is attachedto one pressure connector 26 at the pressure output port 29 of thepressure controller, and the calibrated gauge 7 is attached to the otherpressure connector 27 at the pressure output port 29 of the pressurecontroller. The pressure standard device 6 can be a precision digitalpressure gauge, a digital pressure calibrator, an (absolute pressure)digital pressure gauge, or an intelligent digital pressure calibrator,collectively called standard gauge 60, but it may also be a pressuremodule (pressure sensors 61 and 62). In case of the standard gauge, aplurality of standard gauges with different ranges need to be equipped,and replaced manually at the pressure connector 26. In case of thepressure module, a plurality of pressure modules 61 and 62 may befixedly arranged and communicated with the pressure connector 26 via therespectively connected solenoid valves 31 or 32. The pressure standarddevice 6 (standard gauge or pressure module) is attached to the pressureconnector 26, and for different pressure ranges, the pressure standarddevice is replaced with one of corresponding range (as shown in FIG. 1,a pressure module may be used and communication indicated by the solidline, or alternatively a standard gauge may be used and communicationindicated by the broken line), so that the range of pressure measurementand control is not limited, and the measurement accuracy is not affectedby the measurement range. The pressure standard device 6 is in signalconnection with the pressure controller (refer to FIG. 3), performsreal-time measurement (observation) of gas path pressure in a closedpressure calibration loop, provides real-time transmission of itscontinuous pressure measurement data to the control chip 28 forreal-time control on the output pressure, and takes measurement resultof ultimate control at a certain pressure set point as the standardvalue for pressure calibration, for assignment to the output standardpressure and for display on the display.

The electric signal detection unit 5. When using the standard gauge 60as the pressure standard device 6, a digital pressure calibrator (aprevious invention patent of the company, Chinese Patent No.ZL200610114103.6) can be used as the standard gauge. The digitalpressure calibrator is provided with an electric signal detectionfunction, which is combined with the control chip 28 of the pressurecontrol unit 2 to perform detection and calibration on electric signalsoutput by the calibrated gauge while performing pressure calibration onit, thereby implementing integrated calibration on pressure and electricsignals, and achieving full-automatic pressure calibration.

When using the pressure module (61, 62) as the pressure standard device,a reference can be made to Chinese Patent No. ZL200610114103.6 for theelectric signal detection circuit of the digital pressure calibrator. Astandard electric signal detection circuit is provided to measureelectric signals output by the pressure gauge, and is integrated withthe pressure sensors and the pressure controller to perform detectionand calibration on electric signals output by the calibrated gauge whileperforming pressure calibration on it, thereby implementing integratedcalibration on pressure and electric signals, and achieving portablefull-automatic pressure calibration.

The electric signal detection circuit is shown in FIG. 7. When thestandard pressure of the pressure control unit is applied to thecalibrated gauge, electric signals will be generated at a pressureswitch signal input terminal 71 and an electric signal input and outputterminal 72 thereof. The pressure switch signal input terminal 71 andthe electric signal input terminal 72 are connected to a signalamplifier 52, respectively, to input the generated electric signals tothe signal amplifier 52. Through signal amplification processing of thesignal amplifier 52, an electric signal is input to an A/D converter 51connected thereto, and is then converted into a digital signal throughthe A/D converter 51, the digital signal in turn is input to the controlchip 28 connected thereto. In the control chip 28, through calculationby a calculation formula preset in the control chip 28, a detectedelectric signal value or on/off status information of the pressureswitch is obtained, and is then displayed by the display 91. At thistime, the detected electric signal value may used not only as a displayvalue of the electric signal output by the pressure instrument, but alsoas a calibration value for the electric signal output by the pressureinstrument, and is used to determine the accuracy of the electric signalvalue output by the pressure instrument with respect to the standardvalue, or used to determine the consistency of the electric signal valueoutput by the pressure instrument with a prescribed value. Electricsignal calibration data will also be stored in a memory of thecontroller chip 28.

The on/off signal information of the pressure switch is also used in thecontrol chip for program determination on pressure output valuesmeasured at a corresponding state.

In actual use of the instrument, due to careless operations ofpersonnel, signal lines may be misconnected, and in this instance, aninput electric signal will damage the signal amplifier. To this end, aninput protection circuit 53 is specifically added. Each input electricsignal is protected by the input protection circuit 53, and then entersthe signal amplifier 52 and the A/D converter 51, so as to avoid damageto the circuit. The principle of the input protection circuit 53 isthat, when a problem occurs in the input signal, an impedance of theinput protection circuit 53 will change to form a protective circuit, soas to prevent a too strong electric signal from damaging the signalamplifier 52 and the A/D converter 51, and when the input signal isremoved, the input protection circuit 53 will restore the originalimpedance state. The input protection circuit 53 can be commerciallyavailable.

The standard electric signal detection circuit of the electric signaldetection unit 5 implements measurement, calibration or detection ofhigh accuracy on the electric signals (current, voltage, switch pulse,etc.) output by the calibrated pressure instrument. The electric signalcalibration and detection results and curves are displayed by thedisplay.

The above respective units are interconnected and assembled in thehousing, the placement of which is not particular limited (shown in FIG.1 is only a specific form of assembly), subject to the convenience ofuse. For example, the display, the keyboard and the power switch, thesignal output ports, and the RS232 interface, etc. can be directlyprovided on the surface of the housing, and the inlet port 96 of thehigh pressure gas generating unit 1, the exhaust port 24 of the pressurecontroller 2, the pressure connector 26 along with the pressure standarddevice 6, and the pressure connector 27 along with the calibrated gauge7 can be extended, respectively, out of the housing 9. Of course, thehousing may further be provided with accessories such as covers,handles, straps, etc. for convenience of carry, thereby forming acompact, portable on-site full-automatic pressure calibrationinstrument.

INDUSTRIAL APPLICABILITY

The on-site full-automatic pressure calibration instrument of thepresent invention does not require external gas cylinders. The gaspressure generation unit generates compressed air and input the sameinto a closed pressure calibration pipe of the pressure controller. Thegas pressure control unit performs automatic measurement and regulationon the auto-generated gas pressure. At the pressure output port, acertain accurate gas pressure is output as a standard pressure providedto the pressure instrument to be. calibrated. As a result, measurementand calibration of high accuracy is implemented. The instrument uses itsown battery for power supply, requiring no external AC power source. Thefull-automatic pressure calibration instrument achieves automatedcalibration of pressure instruments and significantly improves workingefficiency while greatly reducing its own weight and volume. Theinstrument can be conveniently carried to field, and can implementon-site calibration on a large number of field used pressureinstruments.

1. A multi-range on-site full-automatic pressure calibration instrument,comprising: a housing; a power switch, a plurality of interfaces, adisplay and a keyboard incorporated at proper positions in the housing;and a gas pressure generation unit, a power supply unit, a pressuredetection unit and a gas pressure control unit incorporated in thehousing, wherein the gas pressure generation unit is a gas pressurizingpump communicated with atmosphere, a pressure output pipe thereof beingcommunicated with the gas pressure control unit; a pressure output portof the pressure control unit is communicated in parallel with twopressure connectors, one for installation of a gauge to be calibrated inthe pressure detection unit and the other for installation of a pressurestandard device in the pressure detection unit, the pressure standarddevice being a manually replaceable standard gauge of a different rangeor a plurality of switchable pressure modules of different ranges; thepressure control unit is in signal connection with the pressure standarddevice in the pressure detection unit, and the power supply unit is inelectrical connection with the gas pressure generation unit, thepressure control unit, and the pressure standard device in the pressuredetection unit, respectively.
 2. The multi-range on-site full-automaticpressure calibration instrument of claim 1, wherein the pressure controlunit comprises a pressure controller and a single-chip microcomputersystem, wherein a gas path portion of the pressure controller includesan intake valve, a buffer, a micro-pressure adjusting mechanism, anexhaust valve, and a standard pressure output port; the standardpressure output port is provided with two pressure connectors connectedin parallel; the intake valve is communicated with a high pressure gasoutput pipe of the gas pressurizing pump; the buffer is a pressureaccommodating chamber used to stabilize and preserve pressurized gasoutput by the intake valve, an outlet port of the buffer is communicatedwith a cylinder in the micro-pressure adjusting mechanism, and a plungerin the cylinder is connected with a screw mechanism; the exhaust valveis installed in a pressure output pipe and is communicated with theatmosphere to discharge gas pressure; and the standard pressure outputport is installed in the pressure output pipe in parallel with theexhaust valve; a control portion of the pressure controller includes apressure regulation driving circuit, which is in electrical connectionwith the power supply unit, and is in signal connection with the intakevalve, the exhaust valve and the screw mechanism; and the single-chipmicrocomputer system includes a control chip loaded with a pressurecontrol algorithm, and is provided with a plurality of interfaces; thecontrol chip is connected to the pressure regulation driving circuit,and controls the pressure output pipe through the driving circuit tooutput a precise standard pressure.
 3. The multi-range on-sitefull-automatic pressure calibration instrument of claim 1, wherein thegas pressurizing pump comprises a motor, an eccentric shaft, a swingrod, a pump body, a left cylinder body and a right cylinder body, apiston rod, and an one-way valve body and a cylinder head attached toeach of the cylinder bodies, wherein the pump body is a connectingmember, the motor is fixed to the pump body, and a motor shaft extendsinto the pump body and is connected with the eccentric shaft; theeccentric shaft is of a cylindrical shape, and has at one end thereof adriving pin deviated from the axis, with the driving pin extendingthrough a mounting hole in the flat-shaped swing rod; the swing rod isconnected to the horizontally disposed piston rod through a screw; thepiston rod is of a cylindrical shape, opposite ends thereof beingmounted with sealing rings and extending into the left and rightcylinder bodies, respectively; the cylinder body is of a cylindricalstructure, and the two cylinder bodies are mounted at opposite ends ofthe pump body, respectively; and each of the cylinder bodies issequentially provided at an outer end thereof with the one-way valvebody and the cylinder head, the one-way valve body being communicatedwith an inner cavity of the cylinder body, and communicated withexternal air or compressed air lines through passages in the cylinderhead.
 4. The multi-range on-site full-automatic pressure calibrationinstrument of claim 3, wherein the piston rod forms sealing, through thesealing rings mounted at the opposite ends thereof, at an inner wall ofthe cylinder bodies; and a swing motion of the swing rod drives thepiston rod to reciprocate within the two cylinder bodies along the axis.5. The multi-range on-site full-automatic pressure calibrationinstrument of claim 4, wherein the outer end of each of the cylinderbodies is mounted with two reversely disposed one-way valve bodies,wherein one of the one-way valve bodies is communicated with theexternal air, and the other of the one-way valve bodies is communicatedwith the compressed air line.
 6. The multi-range on-site full-automaticpressure calibration instrument of claim 5, wherein the one-way valvebody is formed through assembly of a cavity seal body, an elastic arm, ametal pad, and a sealing ring (164), wherein the elastic arm extendsinwardly from the cavity seal body and is coupled with a top end of themetal pad, and a bottom end of the metal pad is fixed with the sealingring.
 7. The multi-range on-site full-automatic pressure calibrationinstrument of claim 2, wherein the pressure standard device is aplurality of pressure modules with different ranges, each communicatedthrough a respective solenoid valve with one of the pressure connectorsat the standard pressure output port of the pressure controller, thesolenoid valve being controlled by the control chip through a valveswitching circuit; the single-chip microcomputer system furthercomprises a pressure module switching element, through which each of thepressure modules outputs data to the control chip via a digitalcommunication interface.
 8. The multi-range on-site full-automaticpressure calibration instrument of claim 2, wherein the plurality ofinterfaces provided in the single-chip microcomputer system are adigital communication interface connected to the pressure standarddevice, a display interface, a keyboard interface, and a RS232 interfaceconnected to an external device.
 9. The multi-range on-sitefull-automatic pressure calibration instrument of claim 7, wherein theplurality of interfaces provided in the single-chip microcomputer systemare the digital communication interface connected to the pressurestandard device, a display interface, a keyboard interface, and a RS232interface connected to an external device.
 10. The multi-range on-sitefull-automatic pressure calibration instrument of claim 1, wherein thepower supply unit is a self-powered system by battery, or an externalpower source.
 11. The multi-range on-site full-automatic pressurecalibration instrument of claim 2, wherein the gas pressurizing pumpcomprises a motor, an eccentric shaft, a swing rod, a pump body, a leftcylinder body and a right cylinder body, a piston rod, and an one-wayvalve body and a cylinder head attached to each of the cylinder bodies,wherein the pump body is a connecting member, the motor is fixed to thepump body, and a motor shaft extends into the pump body and is connectedwith the eccentric shaft; the eccentric shaft is of a cylindrical shape,and has at one end thereof a driving pin deviated from the axis, withthe driving pin extending through a mounting hole in the flat-shapedswing rod; the swing rod is connected to the horizontally disposedpiston rod through a screw; the piston rod is of a cylindrical shape,opposite ends thereof being mounted with sealing rings and extendinginto the left and right cylinder bodies, respectively; the cylinder bodyis of a cylindrical structure, and the two cylinder bodies are mountedat opposite ends of the pump body, respectively; and each of thecylinder bodies is sequentially provided at an outer end thereof withthe one-way valve body and the cylinder head, the one-way valve bodybeing communicated with an inner cavity of the cylinder body, andcommunicated with external air or compressed air lines through passagesin the cylinder head.
 12. The multi-range on-site full-automaticpressure calibration instrument of claim 11, wherein the piston rodforms sealing, through the sealing rings mounted at the opposite endsthereof, at an inner wall of the cylinder bodies; and a swing motion ofthe swing rod drives the piston rod to reciprocate within the twocylinder bodies along the axis.
 13. The multi-range on-sitefull-automatic pressure calibration instrument of claim 12, wherein theouter end of each of the cylinder bodies is mounted with two reverselydisposed one-way valve bodies, wherein one of the one-way valve bodiesis communicated with the external air, and the other of the one-wayvalve bodies is communicated with the compressed air line.
 14. Themulti-range on-site full-automatic pressure calibration instrument ofclaim 13, wherein the one-way valve body is formed through assembly of acavity seal body, an elastic arm, a metal pad, and a sealing ring (164),wherein the elastic arm extends inwardly from the cavity seal body andis coupled with a top end of the metal pad, and a bottom end of themetal pad is fixed with the sealing ring.
 15. The multi-range on-sitefull-automatic pressure calibration instrument of claim 11, wherein thepressure standard device is a plurality of pressure modules withdifferent ranges, each communicated through a respective solenoid valvewith one of the pressure connectors at the standard pressure output portof the pressure controller, the solenoid valve being controlled by thecontrol chip through a valve switching circuit; the single-chipmicrocomputer system further comprises a pressure module switchingelement, through which each of the pressure modules outputs data to thecontrol chip via a digital communication interface.
 16. The multi-rangeon-site full-automatic pressure calibration instrument of claim 11,wherein the plurality of interfaces provided in the single-chipmicrocomputer system are a digital communication interface connected tothe pressure standard device, a display interface, a keyboard interface,and a RS232 interface connected to an external device.
 17. Themulti-range on-site full-automatic pressure calibration instrument ofclaim 15, wherein the plurality of interfaces provided in thesingle-chip microcomputer system are the digital communication interfaceconnected to the pressure standard device, a display interface, akeyboard interface, and a RS232 interface connected to an externaldevice.
 18. The multi-range on-site full-automatic pressure calibrationinstrument of claim 2, wherein the pressure standard device is astandard gauge, the standard gauge being a precision digital pressuregauge or a digital pressure calibrator.
 19. The multi-range on-sitefull-automatic pressure calibration instrument of claim 3, wherein thepressure standard device is a standard gauge, the standard gauge being aprecision digital pressure gauge or a digital pressure calibrator. 20.The multi-range on-site full-automatic pressure calibration instrumentof claim 11, wherein the pressure standard device is a standard gauge,the standard gauge being a precision digital pressure gauge or a digitalpressure calibrator.